ARTICLE
Prurigo pigmentosa (PP) is a type of inflammatory dermatosis characterized
by pruritic, reddish, papular lesions that usually resolve while leaving
gross reticular pigmentation [1]. More than 300 cases have been reported
in Japan [2], and most such lesions are characterized by recurrent pruritic
erythematous papules that resolve, leaving a peculiar, reticulate hyperpigmentation.
In severe cases, however, they may also form edematous infiltrative plaques,
but no formation of vesicles or bullae is generally found [3]. We herein
report a curious case of bullous PP, associated with diabetes mellitus,
which began as a severe vesicular formation.
Case report
A 32-year-old Japanese male was first seen at a dermatological clinic
in October 1997 with a 7-day history of pruritic and painful eruptions
on his chest and back. He had no significant past medical history and
specifically he had a negative atopic history. On examination, multiple,
itchy, painful, vesicular lesions erupting in a disseminated pattern,
showing almost a symmetrical distribution on his back and anterior chest
wall were seen. No mucous membranes were involved. He demonstrated a slight
fever and general fatigue. The patient was given aciclovir (400 mg) three
times daily for five days for a presumed diagnosis of Kaposi's varicelliform
eruption. When he was reexamined three days later, new crops of vesicular
lesions had appeared on his neck, chest and back. He was initially treated
with 0.12% Rinderon VG® (0.12% betamethasone valerate and
0.1% gentamicin sulfate) ointment and oral antihistamines, but with no
appreciable benefit. The next day he again returned to our hospital with
recurrent or exacerbating eruptions. A physical examination revealed mottled
erythema, reticular pigmentation, small red papules and numerous vesicles
on the neck, chest and back (Fig.
1). Some scratch marks were observed on his back and some vesicular
lesions had also become umbilicated and demonstrated crust formation (Fig.
2). A skin biopsy from a vesicle on the anterior chest wall showed
an intraepidermal bulla and a perivascular lymphohistiocytic infiltrate
in the upper dermis (Fig. 3),
but no herpetic giant cells in the bulla. The patient was thus started
on minocycline (200 mg/day) with a diagnosis of PP. As a result, new vesicle
formation stopped within one week.
The patient had complained of extreme thirst
and polyuria for one month. His father had diabetes mellitus. His body
weight was 80 kg and BMI was 29 kg/m2. The results of the following
laboratory tests were either negative or within the normal limits: a full
blood cell count, liver and kidney function tests, total serum protein
determination, and an antinuclear antibody test. Total cholesterol was
150 mg/dl, triglycerol 157 mg/dl, blood glucose 348 mg/dl, HbA1c
10.7%, urinary glucose 3+ and ketone 3+. Islet cell cytoplasmic antibody,
islet cell surface antibody, insulin autoantibody, and anti-Herpes
simplex virus antibody (CF) in his serum were all negative.
The patient was diagnosed as having diabetes mellitus (type 2). He was
thereafter put on a low-carbohydrate diet and was given glibenclamide
(2.5 mg/day) from the second week. By the end of the second week the rash
had almost completely cleared up except for the hyperpigmentation. The
treatment with minocycline was stopped after 4 weeks. A urine specimen
gave a ± test for ketone bodies and a 3+ test for glucose 3 weeks
after starting treatment. A subsequent urinalysis, at 5 weeks was negative
for ketone bodies and glucose. The blood sugar levels continued to be
high during this period (223-256 mg/dl). Nevertheless, no recurrence of
the lesions has been seen during the 2 months follow-up.
Discussion
The cause of PP is unknown. Recently some reports have described patients
with PP associated with ketosis [4-7], fasting [8], dieting [9] and insulin-dependent
diabetes mellitus [10, 11]. Because ketosis is commonly observed in association
with fasting, dieting and IDDM, it may thus be involved in the pathogenesis
of PP [6]. In our case, although, the onset of the eruptions coincided
with the increase of glucose and ketone in the urine, the improvement
in the eruptions did not correlate with the blood sugar levels but instead
with the urine ketone levels. Exacerbation of blood sugar levels could
be also due to the use of topical steroids. Minocycline for the first
week was well tolerated without any side effects. Two months later, his
diabetes was observed to be under good control with glibenclamide and
the total ketone in the blood and urine had decreased to the normal range.
Ketosis may thus be an important etiological factor in PP. In our case,
however, ketosis could be the consequence of the treatment of PP and not
the cause of the skin lesions. PP could be associated only with the diabetes
mellitus.
The most characteristic feature in the present
case was that numerous vesicles and bullae were seen both at the beginning
and throughout the clinical course of the disease. Nagashima described
that the formation of vesicles and bullae is not generally found in PP
[3]. Even though some vesicles and bullae are seen during the clinical
course of PP [4, 5, 7], we had never previously observed PP with a severe
formation of vesicles and bullae, apart from one case reported by Aihara
et al. [9]. Histopathologically, PP often shows a lichenoid tissue
reaction, in which epidermal changes consist of inter- and intracellular
edema and liquefaction degeneration of the basal layer. We therefore diagnosed
the present case as a severe form of PP, since there was marked spongiosis
and spongiotic vesicles and bullae showing intra- and subepidermal bullae.
It seems that a sudden exacerbation of diabetes mellitus was associated
with the severe formation of vesicles and bullae in our case. The findings
of this case therefore may suggest a correlation between diabetes mellitus
and PP.
REFERENCES
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